The development of behaviors which are involved in the genesis and maintenance of human obesity will be studied in infancy. Infants will be selected from families with high or low incidence of obesity. The development of feeding patterns, activity patterns, taste responses and mother-infant interaction will be monitored at birth and at regular visits until children reach two years of age. At this time differences between high and low risk infants will be assessed. The major emphasis of these studies will be on the development of those behaviors which are antecedent to the obese condition. Parallel studies in animal models of obesity will include taste responses, and meal and activity patterns using computerized on-line recording techniques. Developmental changes in feeding patterns and taste resonses will be correlated with adipose tissue morphology. Animal models will include genetically obese rodents and rats made obese by dietary means.